Ask The Trades - SHOWER TRIPPING RCD

Chaddy

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SHOWER TRIPPING RCD
Nov 16^th, 2004, 9:18pm

???My mate has just fitted a 10.5kw shower for me along with a clipsal RCD unit. The problem i've got, is that as soon as you select any kind of temperature setting(i.e. you try to heat the water) the RCD trips!! Also the test button doesn't work on the RCD. Does this indicate a problem internally with the shower or is it the RCD???? ??? The pull switch has been bypassed to make sure that wasn't shorting.

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« Last Edit: Mar 7^th, 2005, 7:54pm by LSpark »

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The_Trician

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Re: SHOWER TRIPPING RCD
Reply #1 - Nov 16^th, 2004, 9:48pm

If the RCD is ok, then it is only doing its job, which infers that your shower installation is faulty - either the cable, or the shower unit itself.

Clipseal is a crap brand but if its new it should be ok first time out.

Your shower unit could have an earth fault, and I'd get this checked out before further use is made of the unit for safety's sake.

TT

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Chaddy GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #2 - Nov 16^th, 2004, 9:54pm Yeah thought clipsal were shite. What do you recommend if and when it needs changing? Why doesn't the test button work??
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The_Trician

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Re: SHOWER TRIPPING RCD
Reply #3 - Nov 16^th, 2004, 10:21pm

MK is the way to go - dear but good.

Reason why test button doesn't work?
Well firstly, the thing has to be switched on.
Secondly, the thing has to be connected up correctly - is your 'mate' a sparky?

If neither of these are not the cause, then the RCD unit itself might be U/S. Its not unusual to find one dead-on-arrival straight out the box, but it is rare.

Is any of this gear second-hand by the way?

TT

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Chaddy GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #4 - Nov 16^th, 2004, 10:25pm All brand new!! He's not a sparky The RCD test button still doesn't trip even when powered up. Should the earth bonding cable from the shower supply pipe go to the CU or the new RCD enclosure?
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The_Trician

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Re: SHOWER TRIPPING RCD
Reply #5 - Nov 16^th, 2004, 10:36pm

The earth in the shower cables botyh to the shower and from the main switch should both go to the RCD earth terminal. You can also run an earth back to the CU if you wish. There should also be a seperate earth connecting the showr to the light fitting and to any exposed metalwork in the bathroom - eg radiator pipes, hot and cold feeds to bath & handbasin. This does not necessarily need to go all the way back to the CU.

The test button will not work unless there is an earth connected.

TT

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Chaddy GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #6 - Nov 16^th, 2004, 10:43pm Thanks TT. Will check this out tomorrow and let you know what the outcome is. Thanks for the advice. Chaddy
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The_Trician Trade Member Offline Posts: 7721 Total Thanks: 8 For This Post: 0 Gender: Trade: Electrician	Re: SHOWER TRIPPING RCD Reply #7 - Nov 16^th, 2004, 10:51pm No worries - good luck. Its my guess that the thing's not been correctly wired/connected. TT
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Beanzy GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #8 - Nov 17^th, 2004, 5:54am Yep and watch out for the neutral on the wrong side of the split bar and/or the U link not taken out of the Neutral bars.
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sparkyjonny

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Re: SHOWER TRIPPING RCD
Reply #9 - Nov 17^th, 2004, 10:35am

[quote author=The_Trician link=1100639906/0#5 date=1100644598]The test button will not work unless there is an earth connected.

TT [/quote]

I thought an earth isn't needed on modern RCDs for testing - it creates an inbalance by linking the load phase with the supply neutral through a resistor? The earth is necessary for effective protection of the shower unit, but not for testing.

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The_Trician Trade Member Offline Posts: 7721 Total Thanks: 8 For This Post: 0 Gender: Trade: Electrician	Re: SHOWER TRIPPING RCD Reply #10 - Nov 17^th, 2004, 11:18am You are probably right mate, but I can't see his actual RCD from here, so am just guessing. TT
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Chaddy

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Re: SHOWER TRIPPING RCD
Reply #11 - Nov 17^th, 2004, 5:58pm

Ok changed the RCD. everything worked great water got hot etc. Put the pull switch back on and it tripped. Thought it must be the switch shorting. Removed it joined the wires turned the power back on and it tripped Cry

and the test button no longer works on this new RCD. Is it possible to blow the RCD and is it repairable????
One other thing the earth bonding wire was fitted to the CU. When i removed it there was a small spark. Is this significant????

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Beanzy

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Re: SHOWER TRIPPING RCD
Reply #12 - Nov 17^th, 2004, 6:14pm

[quote author=Chaddy link=1100639906/0#11 date=1100714321]
One other thing the earth bonding wire was fitted to the CU. When i removed it there was a small spark. Is this significant???? [/quote]

Very!. You may have a neutral to earth short. Get a spark in to have a shufti properly as you may not have the kit to check insulation resistance or measure the current/voltage on that earth. Your earthing in the installation will be live, but may be of high enough impedence not to trip the main fuse immediately. So the short circuit capacity of the circuit and earth continuity will have to be checked too.

Another thing to check visually is the neutral bar at the consumer unit. Is this actually two bars with a feed from the main incoming bar to the secondary RCD bar? Sometimes there is a link between the two.

Do the phase (red or brown) wires all go to the same way number as their corresponding Neutrals and Earths on the respective bars?

I'd whip the L,N &E off the consumer unit for all of that shower circuit until you've had it checked.

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« Last Edit: Nov 17^th, 2004, 6:18pm by Beanzy »

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The_Trician

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Re: SHOWER TRIPPING RCD
Reply #13 - Nov 17^th, 2004, 6:25pm

I know what the problem is - I think?

The clue is in the shower pull switch.

Its my bet that you have L going to L on one side but you have the other L in the N terminal and vice-versa.

Check how your pullswitch is connected up.

Red from mains should go to L and red to shower should go to L-load.

Black from Mains should go to N and Black to shower should go to N-Load.

Also check that your RCD hasn't been cross-connected in the same way.

Dunno if its knackered the RCD or not - you'll have to try it again once you are sure everythings correctly connected.

TT

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sparkyjonny GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #14 - Nov 17^th, 2004, 9:30pm Reverse polarity? Yes - good idea. Could be another fault, but it's a good starting point.
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Chaddy GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #15 - Nov 17^th, 2004, 9:35pm I thought it sounded like the switch, especially as it was fine until the switch was reconnected!! Got a professional coming tomorrow to check it over. Don't want to take any more chances.
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Chaddy GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #16 - Nov 17^th, 2004, 9:45pm Can you give me any ideas how much i can expect to pay to have the installation checked out?? I know it's a difficult question to answer but a ball park figure would help to make sure i don't get ripped off.
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LSpark

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Re: SHOWER TRIPPING RCD
Reply #17 - Nov 17^th, 2004, 11:01pm

[quote author=Chaddy link=1100639906/15#15 date=1100727344]I thought it sounded like the switch, especially as it was fine until the switch was reconnected!!
Got a professional coming tomorrow to check it over. Don't want to take any more chances. Grin

[/quote]

Hey Chaddy

Yep get it checked out properly, as the other guys have already said it's most likely a cross connection.

Quote:

Can you give me any ideas how much i can expect to pay to have the installation checked out??
I know it's a difficult question to answer but a ball park figure would help to make sure i don't get ripped off.

�100 or less

Quote:

Is it possible to blow the RCD and is it repairable?

RCD's arent usualy damaged by this, however they wont reset instantly, with the shower properly disconnected the RCD should reset after turning on and off and waiting some time.

It is important the show is not used for the time being tho as I have concerns about your earthing being live and sparking, if the earthing is poor or mis-wired you may get shocks from exposed conductive parts e.g. metalic pipes etc

Hope you get it all sorted out, do keep us informed how it goes!

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The_Trician Trade Member Offline Posts: 7721 Total Thanks: 8 For This Post: 0 Gender: Trade: Electrician	Re: SHOWER TRIPPING RCD Reply #18 - Nov 18^th, 2004, 3:02am Whole installation? The whole house? A PIR will cost you around �150. Just to check the shower circuit? �30-50. TT
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ban-all-sheds GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #19 - Nov 18^th, 2004, 9:58am The shower is just the load - you can connect it either way round. You shouldn't, as it would mean you'd be switching the neutral inside the shower, but it can't cause problems like these...
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The_Trician Trade Member Offline Posts: 7721 Total Thanks: 8 For This Post: 0 Gender: Trade: Electrician	Re: SHOWER TRIPPING RCD Reply #20 - Nov 18^th, 2004, 10:36am I'm talking about L connected to N and N connected to L when the double pole shower pullswitch is in the ON position - BANG! TT
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Chaddy

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Re: SHOWER TRIPPING RCD
Reply #21 - Nov 18^th, 2004, 9:12pm

All sorted at last!! Grin

The problem was that my mate followed the instructions!!!

They said that a neutral link wire shoud be run from the RCD unit to the CU!!!

Guess what? Removed it and surprise surprise it works perfect!!!! Grin

Thanks to everybody for their thoughts and ideas. Very much appreciated.
This is an excellent forum with some really helpful people.

Cheers guys.

Chaddy

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sparkyjonny GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #22 - Nov 18^th, 2004, 9:19pm Yes, there should be a neutral link - from the CU to the supply side NOT LOAD SIDE of the RCD. I take it this is still in place - unless you've skipped past the RCD, the shower won't work without this!! The instructions probably put the emphasis on this neutral link for 3-phase 3-wire installaitons.
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Chaddy GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #23 - Nov 18^th, 2004, 9:28pm The instruction specifies a separate neutral from the neutral block in the CU to the RCD neutral block!! Already had the neutral fitted to the feed side of the RCD.
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sparkyjonny GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #24 - Nov 18^th, 2004, 9:40pm RCDs don't have a neutral block - there's an incoming live & neutral, and a load live & neutral, with the earths connected together. Maybe your enclosure is a small consumer unit which has a neutral bar fitted?
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LSpark Global Moderator Trade Member Author Offline Posts: 8069 Total Thanks: 3 For This Post: 0 London, UK United Kingdom Gender: Trade: Electrician	Re: SHOWER TRIPPING RCD Reply #25 - Nov 18^th, 2004, 9:52pm Well anyway who cares not it's sorted!! However Jonny is right in that there is no neutral back, what may of happened is he read the instructions and got it slightly confused, this often happens. Well done for getting it all sorted out
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The_Trician Trade Member Offline Posts: 7721 Total Thanks: 8 For This Post: 0 Gender: Trade: Electrician	Re: SHOWER TRIPPING RCD Reply #26 - Nov 18^th, 2004, 10:07pm The contentious 'block' is most likely the Earth terminal strip! TT
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ban-all-sheds

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Re: SHOWER TRIPPING RCD
Reply #27 - Nov 19^th, 2004, 12:32am

[quote author=The_Trician link=1100639906/15#20 date=1100774186]I'm talking about L connected to N and N connected to L when the double pole shower pullswitch is in the ON position - BANG!

TT [/quote]
Ah - I see what you mean now. You mean, in effect, the switch rotated through 90�. I read it as supply in OK, load with reversed polarity.

Sorry.

Must be late though - still can't work out what the instructions meant, and what Chaddy's mate did...

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The_Trician Trade Member Offline Posts: 7721 Total Thanks: 8 For This Post: 0 Gender: Trade: Electrician	Re: SHOWER TRIPPING RCD Reply #28 - Nov 19^th, 2004, 12:57am Nor me! The confused just got even more confusing! TT
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Chaddy GDPR opt-out Total Thanks: 8 For This Post: 0	Re: SHOWER TRIPPING RCD Reply #29 - Nov 19^th, 2004, 9:19am Sorry wasn't clear about the neutral in the RCD. I should have said it went to the neutral block in the enclosure!! It is a separate stand alone unit.
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